Civil Summons from Debt Collector Law firm posing as Creditor on Civil Summons

It's not fraud unless you (or, in some cases, the Court) detrimentally relies on the false representation.  If I lie to you and tell you that the car I'm trying to sell you has only 10,000 miles on it, but you don't believe me nad don't buy the car, you have no civil claim against me for fraud, having suffered no damage from my lie.  Here, you're not relying on the misrepresentation because you know it's a lie.  However, it may constitute champerty - generally, lawyers are not allowed to purchase claims and pursue them - as well as other breaches of an attorneys' ethical responsibilities (e.g. to tell the truth to a Court.)  Moreover, if it is true that Capital One sold its claim to the law firm (frankly, I think the person you spoke to at Capital One made a mistake; more likely it just authorized the law firm to represent it in the case in exchange for a share of any recovery), than Capital One no longer has any right to sue you on the debt.  The case (assuming you can prove that Capital One sold its claim) should be dismissed for lack of standing, and the real owner of the claim would have to commence a new action.